-LRB- CNN -RRB- -- Facebook and Google are battling it out to dominate your smartphone time and , for now , Facebook is winning .

According to the latest stats from comScore , Facebook was the most popular mobile app in the United States in 2012 . The Google Maps app held the top position until October , when Apple rolled out its latest mobile operating system , iOS 6 , and replaced the built-in Google Maps app with its own , less accurate version .

Of course , Facebook also had a hand in its own success . Its number of monthly unique visitors rose steadily over the course of the year . In August , the company rolled out a long overdue revamp of its iOS mobile app for iPhone and iPads , significantly speeding up the launch , scroll and browsing times . User reviews in Apple 's App Store shot up as a result , and in December the company followed up with a better version of its Android app .

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Facebook started 2012 facing criticisms of its mobile strategy , and while there are still lingering questions about how it will make money off of mobile , these stats show its adept at transferring the Facebook experience to tablets and smartphones .

People are n't just opening their Facebook app the most , they 're spending astonishingly large chunks of time in the app , poking around and reading up on their friends . The social network 's app was the single largest , single app time suck , accounting for 23 % of the time people spend using mobile apps , according to comScore . Instagram was a distant second accounting for just 3 % of the time people spend in apps . Google 's app with the most engagement was Gmail , but in total 10 % of users ' time was spent across various Google apps .

The more interesting story in the coming year might be Google 's rise to dominate all mobile platforms , not just its own Android operating system .

Facebook may have the No. 1 spot locked up , but Google apps account for the next five most popular apps . After Maps , Google Play , Google Search , Gmail and YouTube were the top apps on Android and iOS devices in December . Google only re-released an iOS version of its Maps app in December , which could continue to fight back and possibly overtake Facebook in 2013 .

Apple 's only app on the list is iTunes , coming in at 8th place . Rounding out the top 10 list are Pandora Radio , Cooliris and Yahoo! Messenger .

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Facebook had the most popular mobile app for Android and iOS combined in 2012

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Google Maps was in second place followed by five other Google apps

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Facebook had highest levels of engagement , with 23 % of app time spent in the app